In the traditional manufacturing process of the LCD/OLED (Liquid Crystal Display/Organic Light Emitting Diode Display), the glass substrate used is the alkali free glass, for example, for liquid crystal panel of Liquid Crystal Display (LCD), the glass substrates used in the manufacturing process of the array (array substrate) and the color filter (color filter substrate) are alkali free glasses. However, there is generally a little alkali metal like sodium ion and kalium ion contained. The sodium ion or the kalium ion are relatively active, and are easy to react with other substances, thereby resulting in the deterioration of devices.
The alkali may pollute the dielectric material in the TFT gate (Thin Film Transistor gate), thereby reducing the lifetime of the device. The mobility of the sodium ion is the highest and is the most pollutant, therefore, the TFT-LCD requires the alkali free glass as the glass substrate. The sodium ion content of the ordinary alkali free glass is (1−2)×10−3 which is caused by the raw material or the fireproof material. The alkali content requirement of the substrate and the TFT interface is lower than 5×10−5, therefore, the alkali metal content shall be controlled as much as possible.
In the increasingly mature manufacturing process of the Liquid Crystal Display (LCD) panel at present, the cost is an important factor to increase the competitiveness. The glass substrates currently used for global LCD/OLED are monopolized by the Corning, the Asahi Glass, the Nippon Sheet Glass and the Nippon Electric Glass, therefore, the price is high. Because the sodium ion content of the alkali free glass is (1−2)˜10−3, while the alkali content requirement in the panel industry is lower than 5×10−5, the requirement of the glass substrates used for LED/OLED is difficult to meet.